Wasn’t that kind of meddling what got us here in the first place?
Helps to be fully vaccinated and ensure vitamin D is optimum. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7973108/
I believe, but opinions vary wildly, that doing experiments with variations of naturally occurring virii (to try to head off a future threat) is what got us into this mess in the first place.
You're only asking this question because we're in a mass hysteria (see also: "mass formation"). Why didn't we do what you're suggesting during the HK flu in 1968-69? Because it simply wasn't very dangerous, and there isn't much to do about respiratory viruses, so we just took our lumps and got on with life without devastating liberty or the global economy.
We could have done that this time, too, and should have, but central planners needed something to use as an excuse to "reimagine" things without having to go through all the trouble of gaining our approval and consent.
Our science is not that good.
Basically you want a virus that really is a vaccine. The current vaccines are far from perfect because apparently we don't know how to make them better. Expressing such a vaccine as a contagious virus would not better but would only create more risks.